Polyalkeneoxides and polyvinyl-pyrrolidones mobility control agent and process

ABSTRACT

In a supplemented oil recovery process and other uses, flow resistance of aqueous polyalkeneoxide solutions, e.g., Polyox WRS-301, can be increased by adding high molecular weight homopolymers, or random block or heteropolymers of polyvinylpyrrolidones.

United States Patent 1 11 3,776,310

Norton et a1. Dec. 4, 1973 [54] POLYALKENEOXIDES AND 3,018,826 1/1962Sandiford 166/273 POLYV[NYL PYRROLIDONES MOBILITY 2,335,454 11/1943Schuster et a1. 260/883 X CONTROL AGENT AND PROCESS 3,634,305 1/1972260/29.2 X

[75] Inventors: Charles J. Norton; David 0. Falk, 3,085,063 4/1963Turbak 252/8 .55 X

both of Denver, C010.

[73] Assignee: Marathon Oil Company, Findlay, Primary Emminer flerben BGuynn I Ohm AttorneyJoseph C. Herring, Richard C. Willson, Jr.- [22]Filed: May 6, 1971 and Jack L. Hummel 211 Appl. No.2 140,931

52 U.S.C1 ..166/275,166/273,166/274, ABSTRACT 252/855 D [51] Int. ClE21b 43/22 In a supplemented oil recovery process. and other uses, [58]Field of Search 252/855 D; 166/274, 1 flow resistance of aqueouspolyalkeneoxide solutions,

166/275 e.g., Polyox WRS-30l, can be increased by adding high molecularweight homopolymers, or random [56] References Cited block orheteropolymers of polyvinylpyrrolidones.

UNITED STATES PATENTS 3,116,791 1/1964 Sandiford et a1. 166/274 7Claims, 1 Drawing Figure PATENTEU DEC 4 I973 3, 776, 310

60 I I I H: O Q [L 30 Z LLI LIJ [I U 0') PVP 500 400 300 200 I00 0THICKENER WEIGHT, ppm

BLENDS OF POLYETHYLENE OX/DE (PO) AND POLYV/NYLPYRROL/DONE (PVP) /NWATER EXHIBIT SYNERG/SM ON SCREEN FACTOR.

6. J NORTON 6 0. 0. FAIL/f POLYALKENEOXIDES AND POLYVINYL-PYRROLIDONESMOBILITY CONTROL AGENT AND PROCESS CROSS REFERENCES TO RELATEDAPPLICATIONS The following cases relate to the same general field asthat of the present invention: U.S. Pat. No. 3,507,331; U.S. Pat. No.3,467,187 Ser. No. 74,336 filed Sept. 22, 1970, now Pat. No. 3,677,344Ser. No. 67,726 filed Aug. 28, 1970, now Pat. No. 3,670,820; Ser. No.79,591 filed Oct. 9, 1970, now Pat. No. 3,692,l l3 and Ser. No. 85,064filed Oct. 29, 1970, now Pat. No. 3,684,014.

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates primarily to wells classified in Class 166 of the U.S.Patent Office, and more particularly to production of earth fluid bydriving fluid classified in Class 166 subclass 252.

2. Description Of The Prior Art Polyalkeneoxides such as polyethyleneoxides are described in the Union Carbide Corporation bulletins on theirproduct Polyox, e.g., their Bulletin F-40246E, 10M-1968. The use ofpolyalkeneoxides, e.g., polyethyleneoxide, especially for thepreparation of displacement fluids for use in secondary and tertiaryrecovery of petroleum from subterranean formations has been taught in avariety of prior art patents. U.S. Pat. No. 3,399,725 teaches use ofpolyethylene oxide improving water flooding processes. U.S. Pat. No.2,842,492 teaches the use of copolymers such as methacrylic acid withmethyl methacrylate, ethyleneglycol methacrylate styrene andacrylonitrile, in waterflooding processes. U.S. Pat. No. 2,771,138teaches the recovery of oil from subterranean oil reservoirs usingdissolved sugar and a water soluble salt of a metal selected from theclass consisting of aluminum, lithium, and berylium. U.S. Pat. No.3,039,529 teaches selective partially hydrolyzed polyacrylamides butpresents no specific information relating to homopolymers, randomheteropolymers, or block heteropolymers of polyalkene oxides. U.S. Pat.No. 3,208,518 teaches that poly-- mer solutions are less viscous andmore injective at pH below 5; U.S. Pat. No. 2,827,964 teaches partiallybydrolyzed polyacrylamides but mentions no mixture of homopolymers,random heteropolymers, or block heteropolymers of polyalkene oxides,U.S. Pat., No. 3,002,960 prepares polyacrylamides for well injection tobe resistant to connate brine and to absorption on formation rock butmakes no mention of polyalkeneoxide; U.S. Pat. No. 3,074,481 isprimarily concenred with well patterns and mentions no polyalkeneoxide;U.S. Pat. No. 3,139,929 is also primarily concerned with floodinggeometry and use of water-soluble polymers thereof; U.S. Pat. No.3,210,310 teaches in situ' polymerization to give partial pluggingaround a well bore but mentions no polyalkeneoxide; U.S. Pat. No.3,476,186 teaches flooding with acrylic acidacrylamide-diacetoneacrylamide 'copolymer but mentions no polyalkeneoxide. Moreover, factorsinfluencing mobility control by polymer solutions are discussed in PaperNo. SPE 2867 of the Society of Petroleum Engineers of the AmericanInstitute of Mining Engineers, which paper also describes the screenviscometer and screen factor discussed later in this application.However, none of the prior art, to the best of our knowledge, teachesthe improved resistance factors (screen factors) and mobility control ofaqueous polyvinylpyrrolidone solutions obtained by mixing synergisticamounts of polymers containing random heteropolymers or block heteropolymers of polyethylene oxide and polypropylene oxide, as includedwithin the present invention.

SUMMARY General Statement of the Invention Polyalkeneoxide polymers andpolyvinylpyrrolidones alone, i.e., polyvinylpyrrolidone (PVP), have beenused as thickening agents to increase the viscosity of liquids.Polyethyleneoxide has been used as a displacing liquid in secondarypetroleum recovery. Such uses are taught, for example, in Union Carbidesbulletin, supra, and in U.S. Pat. No. 3,116,791. These polyalkeneoxidesdecrease the mobility of the displacing liq-- uids to improve theirefi'iciency in displacing oil-inplace from formations and moving the oiltoward production wells. Decreasing the mobility of the displacingfluids minimizes fingering or channeling of a displacing fluid throughthe body of oil-in-place in the formation.

A laboratory method for obtaining a measure of the relative mobility offluids is described in the American Institute of Mining Engineers paperFactors Influencing Mobility Control by Polymer Solution by R. R.Jennings, J. H. Rogers, and T. J. West, Society of Petroleum EngineersPaper No. 2867 prepared for the Ninth Biennial Production TechniquesSymposium, held in Wichita Falls, Tex., May 14-15, 1970. I

In the testing, the liquids flow through screens and the ratio of thetime required for the test solution to flow through the screenviscometer divided by the time required for a standard solvent (water)to flow through the viscometer is termed the screen factor.

According to the present invention, the screen factor and mobilitycontrol of aqueous solutions of polyalkeneoxide, e.g., polyethyleneoxide, can be inexpensively and effectively increased by the addition ofa polyvinylpyrrolidone, (see polyvinylpyrrolidone Technical Bulletin7543-1 13, General Aniline and Film Corporation, West 51 Street, NewYork, NY. 10020) e.g., polyvinylpyrrolidone (PVP), having a molecularweight in the range of from about 10 to about'10, more preferably from10 to about 10 and most preferably from 1 X 10 to about 6 X 10 Thepresent invention is useful with any of the general class ofpolyalkeneoxides. The preferred polyalkeneoxides have molecular weightsof from 10 -10 and more preferably from 10 l0 and most preferably from 3X 10 6 X 10 Polyalkene oxide may be a homopolymer, e.g., poly-- ethyleneoxide, or a random or block hetero polymer,

e.g., Pluronic F-127 produced by the Wyandottev C. R. Smith, (Reinhold,1966) should be consulted in this connection.

BRIEF DESCRIPTION OF THE DRAWINGS The FIGURE is a plot of screen factorversus polyethylene oxide (PO) at various levels of parts per million ofpolyvinylpyrrolidone (PVP) showing the unexpected increase in screenfactor value from the expected linear results.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Starting Materials As mentionedabove, the polyalkeneoxides will preferably have molecular weights inthe range of from about 10 to about more preferably from 10 to 10" andmost preferably from 3 X 10 to 6 X 10. Preferably the polyalkeneoxideswill be present in amounts of from 0.001 to about 10.0, more preferablyfrom 0.01 to about 1.0, and most preferably from 0.02 to about 0.2weight percent based on the weight of the total solution. Thepolyvinylpyrrolidone derivative will preferably have molecular weightsin the range of from 10 to 10 and more preferably from 10 to 10 and mostpreferably from 1 X 10 to about 6 10. Preferably, thepolyvinylpyrrolidone will be present in amounts of from 0.001 to about10, more preferably from 0.01 to about 1.0, and most preferably from0.02 to about 0.2 weight percent based on the total solution. The amountof polyvinylpyrrolidone derivative will generally be in the range offrom about 10 to 100,000, more preferably from 100 to 10,000 and mostpreferably from about 200 to 2000 parts by weight per million parts ofsolution.

The amount of polyalkeneoxide will generally be in the range of 10 to100,000, more preferably from 100 to about 10,000 and most preferablyfrom about 200 to 2,000 parts by weight per million parts of solution.

By polyalkeneoxide is meant herein any of the polymeric water-solubleresins prepared by homopolymerization of a single alkene oxide, forexample ethylene oxide, propylene oxide, butylene oxides, having polymerweights of 10 to 10 While any of the polymerized alkene oxides(preferably lower alkene oxides) may be employed in the practice of theinvention, it is preferred to employ the homopolymer of polyethyleneoxide. This product is made commercially by Union Car bide ChemicalsCompany under the trade name Polyox. Mixed poly(alkeneoxides), (made byheteropoLymerization of more than one alkene oxide in either a random orblock polymerization), may also be employed.

The solvent for the liquid solutions of the present invention willcomprise water, most preferably consist TABLE 2.PREPARATION OF CORES FORTHICKENED WATER essentially of connate water, example, Palestine linewater, fresh water, or brackish water. It is preferable that the watercontain less than about 300,000, more preferably less than about 10,000,and most preferably less than about 500 parts per million of dissolvedsolids.

While not necessary to the practice of the present invention, variousother ingredients including among others, cellulose and surfactants,e.g., polyalkylaryl sulfonates and other conventional displacement fluidadditives may be added to the liquid polymer solutions. In addition topolyalkeneoxides, other viscosity increasing agents, e.g.,carboxymethylcellulose or other biopolymers may be employed. Any of theaforementioned specific ingredients may be employed in admixture.Preparation of Liquid Systems It will generally be preferable to merelyco-mix the non-aqueous polyalkeneoxide and the polyvinylpyrrolidonederivative as defined below, and then add water while gently stirring topromote dispersion, suspension, and solution. Bubbling a small amount ofnonoxygen gas, e.g., natural gas, may be used to effect mild stirring.The ingredients will preferably be mixed at a room temperature somewhatabove room temperature, more preferably from 0C. to about C., and mostpreferably from 20C to about 50C. If desired, a mixing operation can beemployed in one or more full-type mixers or mixing tees so long as theproportions of the ingredients are properly measured and thoroughlymixed.

EXAMPLE I Aqueous solutions of polyvinylpyrrolidone and poly(ethyleneoxide), e.g., Polyox, are prepared by weighing both solids intoa bottle, adding deionized water, stirring slowly with a magnetic barfor several hours until visibly dissolved, and then allowing to standfor 1 day. Testing for screen factor is done according to Society ofPetroleum Engineers Paper No. 2867, discussed supra, and the proportionsand test results are summarized in Table l and the FIGURE.

TABLE 1 Poly(ethyleneoxide) Polyvinylpyrrolidone I Screen Factor 100 ppm400 ppm 20.67 250 ppm 250 ppm 43.41 400 ppm 100 ppm 4081 EXAMPLES II IVThree, 3-inch diameter by 4-foot long Berea sandstone cores are preparedby procedure summarized in Table 2. The preparative core data indicatethat the pore volumes and porosities are comparable. The comparativesecondary waterflood also give very closely comparable initial oil (0,),water (W saturations, residual oil (0,), and water (W saturations forthese three secondary waterflood floods.

FLOODS Core Data Secondary Water Flood 1 Tertiary flood withPermeablllty, water thickener [500 Example PV, cc. Porosity md. Oi Wt 0,WI p.p.m.]

Il 1,030 0.220 415. 0 0.65 0.35 0. 37 0.63 PVP. Ill 1,065 0.220 366 0.61 0.38 0. 38 0. 62 .250 p.p.m. PVP.

250 p.p.m. PO. 1V 1, 080 0. 210 325. 0 0. 57 0. 40 0. 36 0. 64 PO 1 4ft.X3in. Boron. fired at 825 F.. saturated with Henry brine (i.e.,connato brine having 11,000 p.p.rn 01-, 6.500 p.p.m. Na .376 p.p.m. Ca,167 p.p.m. Mg") and crude oil (7 cp. at ambient temperature) to oilinitial (0i) and water (\Vi); subsequently water flooded to residualsaturations (O and W.) and than llnodad at rates of3.7 (day) and 1.1!(night) ltJday with synthetic Palestine Water" containing 400 p.p.m.N101 and 55 p.p.m. (1101; and 500 p.p.rn. thickener.

Three thickened waters are prepared by dissolving (1) 500 ppm Polyox(PO), (2) 250 ppm Polyox and 250 polyvinylpyrrolidone (PVP), (3) 500polyvinylpyrrolidone, each respectively in synthetic Palestine water.After solution, up'to 1.00 pore volume of each of these thickened watersis used to carry out the tertiary flood. Each of the cores is equippedwith pressure transducers at the front end, middle and end of the coreand a history of readings is taken as the injection proceeds. Thereciprocal mobility values are calculated by means of the Darcyequation,

reciprocal mobility =kXA(AP)/q l where k is the permeability, A is thecross-sectional area in cm AP is the pressure change in atmospheres, qthe throughput flow rate in cm lsec, and l is the length of the core.The reciprocal mobility measured at the front (injection port) showspronounced synergistic effect of polyvinylpyrrolidone on Polyox (PO)over the region of 0.0 1.0 PV. Synergism becomes apparent at the middleand terminal port after 0.1 pore volume is injected. The effectivenessof this reciprocal mobility maintenance is also reflected in synergisticimprovement in oil production for 0.05 to 2.0 pore volumes of 250 ppmpolyvinylpyrrolidone 250 ppm Polyox thickened water injected.

The reciprocal mobility value will increase unusually in the range offrom 5 to about 100 reciprocal millidarcies in the range of from 0.1 to1.0 pore volumes throughput. Use of the specific ranges of concentrationtaught in the present specification in combination with the particularlypreferred ranges of pore values results in a secondary or tertiaryrecovery operation of especially unexpectedly high efficiency.

Modifications It will be understood by those skilled in the art that thepolyvinylpyrrolidone utilized in the examples herein are merelypreferred examples of the variety of polyvinylpyrrolidone derivativesused as permeability modifying agents which may be employed with thepresent invention. Other such polyvinylpyrrolidone permeabilitymodifying agents include homo and heteropolymer derivatives ofsubstituted vinyl pyrrolidones below.

where R may be the same or different, containing from zero to 20 carbonatoms, and are each selected from the group consisting of hydrogen,alkyl, aryl, alkoxyl and halogens of the thereforegoing. Most preferredwhere Rs 1 through 9 each are comprised of hydrogen or'from one to sixcarbon atoms;

A useful modification .of the invention is to vary the relativeproportions of the polyvinylpyrrolidone derivative in the viscosityincreasing solution, for example, using a solution containing nearly 100percent polyvinylpyrrolidone solute at the leading edge of thedisplacement slug and gradually using a higher and higher equivalentpercentage of polyethyleneoxide to provide a slug which is rich in thedepletable component, polyvinylpyrrolidone at its leading edge wheredepletion is most likely to occur. Initial viscosity'of the slug may bethe same at all points throughout the slug or may be itself graduallydecreased until it approaches that of the drive fluid which displacesthe slug through the formation.

Of course, slugs of other displacement fluids, e.g., soluble oils andother micellar solutions, emulsions, etc. be injected prior to thesolution of the invention where desirable.'Similarly, drive fluids,e.g., water mobility buffers followed by water, etc. can be injectedafter the fluids of the present invention. Also the fluids of theinvention can be used to displace slugs of other fluids through theformation and can themselves be driven by other fluids.

What is claimed is:

1. A process for the displacement of oil in oil-bearing formationcomprising injecting into said formation an aqueous solution comprisedof about 0.001 to about 10.0 percent by weight of water-solublepolyethyleneoxide polymer having molecular weight in the range of fromabout 10 to about 10 and 0.001 to about 10 weight percent water-solublepolyvinylpyrrolidone having a molecular weight of from about 10 to about10 2. A process according to claim 1 wherein the aqueous solutioncontains from about 10 to abo ut.5,000 parts per million of polyethyleneoxide and about 10 to about 5,000 parts per million ofpolyvinylpyrrolidone.

3. A process according to claim 2 wherein the solution contains fromabout 200 to about 500 parts per million of polyethylene oxide and fromabout 10 to about 300 parts per million of polyvinylpyrrolidone.

4. A process according to claim 1 wherein the polyvinylpyrrolidone has amolecular weight above 100,000.

5. A process according to claim 1 wherein said polyethylene oxide has amolecular weight above 100,000.

6. A process according to claim 1 wherein said polyethylene oxide has aconcentration of 0.01 to about 1 percent by weight based on the weightof the total solution.

ethylene oxide has a concentration of 0.02 to about 0.2 percent byweight based on the weight of the total solution.

7. A process according to claim 1 wherein said poly-

2. A process according to claim 1 wherein the aqueous solution containsfrom about 10 to about 5,000 parts per million of polyethylene oxide andabout 10 to about 5,000 parts per million of polyvinylpyrrolidone.
 3. Aprocess according to claim 2 wherein the solution contains from about200 to about 500 parts per million of polyethylene oxide and from about10 to about 300 parts per million of polyvinylpyrrolidone.
 4. A processaccording to claim 1 wherein the polyvinylpyrrolidone has a molecularweight above 100,000.
 5. A process according to claim 1 wherein saidpolyethylene oxide has a molecular weight above 100,000.
 6. A processaccording to claim 1 wherein said polyethylene oxide has a concentrationof 0.01 to about 1 percent by weight based on the weight of the totalsolution.
 7. A process according to claim 1 wherein said polyethyleneoxide has a concentration of 0.02 to about 0.2 percent by weight basedon the weight of the total solution.